In the art of controlling a submersible pump with a float switch assembly, for example, as disclosed in U.S. Pat. Nos. 4,215,975 and 4,302,641, it is common to use a hollow float bulb or shell which is adapted to float on the surface of the water or liquid being pumped. The shell is attached to the outer free end of a flexible electrical cord which conducts the power for operating the pump. The float bulb or shell is fluid-tight and encloses a control switch which moves between closed and open positions in response to tilting of the float shell as the liquid level changes between predetermined upper and lower limits.
Usually, the control switch consists of a mercury actuated switch such as disclosed in above mentioned U.S. Pat. No. 4,215,975. However, the commonly used mercury switches are limited in the amount of current which they can conduct, and this limits the size of the electric pump motor which can be controlled directly by a mercury switch. In addition, there is an environmental problem when it is desired to disposed of a mercury switch which has failed and been replaced. Thus in place of a mercury switch, it has been proposed to use a reed-type switch which is actuated by a permanent magnet movable in response to tilting of the float shell, for example, as disclosed in U.S. Pat. No. 4,021,144. However, such a reed switch is also limited in the amount of electrical current which it can effectively conduct and is not suitable for use in controlling relatively large horsepower submersible pumps.